The Ural Mountains

The Ural Mountains are a mountain system between the East European and West Siberian Plains. The length is more than 2000 (with Pai-Khoi and Mugodzhary - more than 2600) km, width from 40 to 150 km.

Geological structure

The Ural mountains were formed in the late Paleozoic in the era of intensive mountain building (Hercynian folding). The formation of the Ural mountain system began in the Late Devonian (about 350 million years ago) and ended in the Triassic (about 200 million years ago). It is an integral part of the Ural-Mongolian folded geosynclinal belt. Deformed and often metamorphosed rocks of mainly Paleozoic age appear on the surface within the Urals. The thicknesses of sedimentary and volcanic rocks are usually strongly crumpled, broken by tears, but on the whole they form meridional bands, which determine the linearity and zonality of the structures of the Urals. From the west to the east stand out:

Pre-Ural marginal trough with comparatively flat bedding of sedimentary strata in the western side and more complex in the east; Zone of the western slope of the Urals with the development of intensively crushed and disturbed sedimentary sequences of the lower and middle Paleozoic; The Central Ural uplift, where among the sedimentary sequences of the Paleozoic and Upper Precambrian, the more ancient crystalline rocks of the edge of the East European Platform appear in places; The system of deflections-synclinoria of the eastern slope (the largest are the Magnitogorsk and Tagilsky), made mainly by the Middle Paleozoic volcanic strata and marine, often deep-sea sediments, as well as by breakthrough deep-seated igneous rocks (gabbroids, granitoids, less often alkaline intrusions) - so-called. Greenstone belt of the Urals; Ural-Tobol anticlinorium with outcrops of older metamorphic rocks and extensive development of granitoids; East-Ural synclinorium, in many respects similar to Tagil-Magnitogorsk.

At the base of the first three zones, according to geophysical data, the ancient, Early Precambrian, foundation, composed mainly of metamorphic and magmatic rocks and formed as a result of several folding epochs, is confidently traced. The most ancient, supposedly Archean, rocks come to the surface in the Taratashsky protrusion on the western slope of the Southern Urals. Doordovik rocks in the foundation of the synclinoria of the eastern slope of the Urals are unknown. It is assumed that the basement of the Paleozoic volcanogenic strata of the synclinoriums is the powerful plates of the hyperbasites and gabbroids, sometimes appearing on the surface in the massifs of the Platinum Belt and other related belts; These plates, perhaps, are the rejectors of the ancient ocean bed of the Ural geosyncline. In the east, in the Ural-Tobolsk anti-clinorium, the outcrops of Precambrian rocks are quite problematic. Paleozoic deposits of the western slope of the Urals are represented by limestones, dolomites, sandstones formed in conditions of mostly shallow seas. In the east of the interrupted belt, more deep-sea sediments of the continental slope can be traced. Still east, within the eastern slope of the Urals, the Paleozoic (Ordovician, Silurian) section begins with altered volcanic rocks of basalt composition and jasper, comparable to the rocks of the bottom of modern oceans. In places higher in the section there are powerful, also changed spilite-sodium-liparite strata with deposits of copper-pyrite ores. The younger sediments of the Devonian and partly of the Silurian are mainly represented by andesite-basalt, andesite-dacite volcanics and greywackes, responsible for the development of the eastern slope of the Urals stage, when the oceanic crust was replaced by a transition-type cortex.

Carboniferous deposits (limestones, grau-vaccines, acidic and alkaline volcanics) are associated with the most late, continental stage of development of the eastern slope of the Urals. At the same stage, the bulk of the Paleozoic, essentially potassium, granites of the Urals, which formed pegmatite veins with rare valuable minerals, also penetrated. In the late Carboniferous-Permian time, sedimentation on the eastern slope of the Urals almost ceased and a folded mountain structure was formed here; On the western slope at that time the Pre-Ural marginal trough was formed, filled with a thick (up to 4-5 km) thickness of detrital rocks that had been demolished from the Urals - molasses. Triassic deposits were preserved in a number of basin-grabens, the occurrence of which in the north and east of the Urals was preceded by basalt (trap) magmatism. The younger layers of the Mesozoic and Cenozoic deposits of the platform nature of the hollow overlap the folded structures along the periphery of the Urals. It is assumed that the Paleozoic structure of the Urals was laid in the late Cambrian - Ordovician as a result of the splitting of the Late Precambrian continent and the expansion of its debris, resulting in the formation of a geosynclinal depression with bark and sediments of the oceanic type in its interior. Subsequently, the expansion was replaced by compression and the oceanic basin began to gradually close and "overgrow" the newly emerging continental crust; Accordingly, the nature of magmatism and sedimentation changed. The modern structure of the Urals bears traces of severe compression, accompanied by a strong transverse contraction of the geosynclinal cavity and the formation of shallow scaly thrusts - burrs.

Minerals

Ural is a treasury of various minerals. Of the 55 species of the most important minerals that were developed in the USSR, 48 is represented in the Urals. The most characteristic deposits for the eastern regions of the Urals are copper ore deposits (Gaiskoye, Sibayskoye, Degtyarskoye deposits, Kirovgradskaya and Krasnouralsk group of deposits), skarn-magnetite (Goroblagodatskoye, Vysokogorskoye, Magnitogorskoye deposits), titanium-magnetite (Kachkanarsky, Pervouralskoye), oxide nickel ores Orsko-Khalilovskoye deposits) and chromite ores (Kempirsay massif deposits), confined mainly to the greenstone belt of the Urals, coal deposits (Chelyabinsk Coal Basin Yen), placers and indigenous gold deposits (Kochkarskoye, Berezovskoye) and platinum (Isovskie). Here are the largest bauxite deposits (North-Ural bauxite region) and asbestos (Bazhenovskoye). On the western slope of the Urals and in the Urals there are coal deposits (Pechora coal basin, Kizel coal basin), oil and gas (Volga-Ural oil and gas area, Orenburg gas condensate field), potassium salts (Verkhnekamskiy basin). Especially the Urals is famous for its "gems" - precious, semiprecious and ornamental stones (emerald, amethyst, aquamarine, jasper, rhodonite, malachite, etc.). In the bowels of the mountains contains more than two hundred different minerals. From the Ural malachite and jasper, the cups of the St. Petersburg Hermitage are made, as well as the interior decoration and the altar of the Church of the Savior on Blood.